In recent years, the significant technological advancement in digital video devices has given more opportunities to record on a recording medium such as a DVD and a hard disk or to distribute on the Internet video signals (a plurality of video pictures aligned in time series), by compressing and coding the video signals. There is H.264/AVC (MPEG-4 AVC) as an image coding standard, and HEVC (High Efficiency Video Coding) standard is under consideration as a next-generation standard (see Non Patent Literature (NPL 1)).